Raney copper

ABSTRACT

Raney copper which is doped with at least one metal from the group comprising iron and/or noble metals is used as a catalyst in the dehydrogenation of alcohols.

This application claims priority to EP Application No. 00 103 546.8,filed on Feb. 18, 2000, and U.S. Provisional Application No. 60/198,755,filed Apr. 21, 2000, the subject matter of each of which is herebyincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to Raney copper, to a process for the productionthereof and to a process for dehydrogenating alcohols.

2. Background Information

It is known to dehydrogenate diethanolamine to yield iminodiacetic acid(U.S. Pat. No. 5,689,000; WO 96/01146; WO 92/06949; published patentapplication JP 091 55 195; U.S. Pat. No. 5,292,936; U.S. Pat. No.5,367,112; CA 212 10 20).

SUMMARY OF THE INVENTION

The present invention provides Raney copper which is characterised inthat it is doped with at least one metal from the group comprising ironand/or noble metal.

Doping may be achieved both by alloying the doping element with theRaney alloy, which consists of copper and aluminium, and by impregnatingthe previously prepared Raney copper with the doping element.

The Raney copper according to the invention may contain the dopingelements in a quantity of 10 ppm to 5 wt. %. Noble metal doping mayamount to 10 to 50000 ppm, preferably 500 to 50000 ppm. The dopingmetals may be selected from the group comprising iron and palladium,platinum, gold, rhenium, silver, iridium, ruthenium and/or rhodium.

The Raney copper according to the invention may comprise meso- andmacropores, but no micropores.

The initial formed alloy can contain more than 50% Cu so that thefinished catalyst contains more residual Al than normally found underthe same activation conditions.

The initial formed alloy can be heat treated in air temperatures higherthan 500° C. activation.

The initial formed alloy can contain more than 50% Cu and heat treatedin air temperatures higher than 500° C. before activation.

The average particle size of the Raney copper according to the inventionmay be 35±30 μm.

The average particle size of the Raney copper according to the inventionis of significance during use in oxidation reactions or alcoholdehydrogenation reactions.

On repeated use, known Raney copper forms granules (agglomerates), sodeactivating the Raney copper.

The Raney copper according to the invention doped with iron and/or noblemetal is not deactivated by unwanted granulation. Advantageously, theRaney copper according to the invention may readily be filtered.

The Raney copper according to the invention exhibits greater activity inthe dehydrogenation of ethylene glycol than the Cr/Raney copperaccording to EP 0 620 209 A1 or U.S. Pat. No. 5,292,936.

The Raney copper according to the invention furthermore advantageouslycontains no toxic metals, such as chromium for example.

The present invention also provides a process for the production of theRaney copper, which process is characterised in that a copper/aluminiumalloy is activated by means of an aqueous sodium hydroxide solution, thecatalyst is washed, suspended in water, an iron salt or noble metal saltsolution is added to this suspension, the pH value of the solution isadjusted to a value from 4 to 11, the catalyst is separated from thesolution and washed.

The present invention also provides a process for the production of theRaney copper, which process is characterised in that the doping metal isalloyed together with copper and aluminium, is then activated by meansof aqueous sodium hydroxide solution and the catalyst is washed.

The present invention also provides a process for the catalyticdehydrogenation of alcohols to their corresponding carbonyls andcarboxylic acids, which process is characterised in that a Raney copperdoped with iron or noble metal is used as the catalyst.

The process according to the invention for the dehydrogenation ofalcohols may be used for dehydrogenating glycols and/or aminoalcohols.The catalyst may be used in the form of a suspension for such reactions.

The alcohols which may be dehydrogenated according to the invention maybe mono- or polyhydric alcohols. Said alcohols, including polyetherglycols, may be aliphatic, cyclic or aromatic compounds which react witha strong base to yield the carboxylate.

It is necessary in this connection that the alcohol and the resultantcarboxylate are stable in a strongly basic solution and that the alcoholis at least somewhat soluble in water.

Suitable primary, monohydric alcohols may include: aliphatic alcohols,which may be branched, linear, cyclic or aromatic alcohols, such as forexample benzyl alcohol, wherein these alcohols may be substituted withvarious groups which are stable in bases.

Suitable aliphatic alcohols may be ethanol, propanol, butanol, pentanolor the like.

According to the invention, glycols may be oxidised or dehydrogenated toyield carboxylic acids. Glycols may, for example, be:

-   -   ethylene glycol    -   propylene glycol    -   1,3-propanediol    -   butylene glycol    -   1,4-butanediol

It is thus possible, for example, to dehydrogenate ethylene glycol toyield glycolic acid (monocarboxylic acid) and to produce thedicarboxylic acid oxalic acid by subsequent reaction with KOH.

Aminoalcohols may also be dehydrogenated with the doped Raney copperaccording to the invention to yield the corresponding aminocarboxylicacids. The amino alcohols may have 1 to 50 C atoms.

It is accordingly possible, for example, to dehydrogenateN-methylethanolamine to yield sarcosine; THEEDA(tetrahydroxyethylethylenediamine) to yield the tetrasodium salt of EDTA(ethylenediaminetetraacetate); monoethanolamine to yield glycine;diethanolamine to yield iminodiacetic acid; 3-amino-1-propanol to yieldbeta-alanine; 2-amino-1-butanol to yield 2-aminobutyric acid.

In one embodiment of the invention, the process according to theinvention may be used to dehydrogenate-aminoalcohols of the formula

in which R¹ and R² each mean hydrogen; hydroxyethyl; CH₂CO₂H; an alkylgroup having 1 to 18 C atoms; an aminoalkyl group having 1 to 3 C atoms;a hydroxyalkylaminoalkyl group having 2 to 3 C atoms andphosphonomethyl.

The aminoalcohols which may be used according to the invention areknown. If R¹ and R² are hydrogen, the aminoalcohol is diethanolamine.

If R¹ and R² are hydroxyethyl, the aminoalcohol is triethanolamine. Theresultant aminocarboxylic acid salts of these starting aminoalcoholsshould be the salts of glycine, iminodiacetic acid and nitrilotriaceticacid respectively. Further aminoalcohols comprise N-methyl-ethanolamine,N,N-dimethylethanolamine, N-ethylethanol-amine, N-isopropylethanolamine,N-butylethanolamine, N-nonylethanolamine, N-(2-aminoethyl)ethanolamine,N-(3-aminopropyl)ethanolamine, N,N-diethylethanolamine,N,N-dibutylethanolamine, N-methyldiethanolamine, N-ethyl-diethanolamine,N-isopropyldiethanolamine, N-butyl-diethanolamine,N-ethyl-N-(2-aminoethyl)-ethanolamine,N-methyl-N-(3-aminopropyl)ethanolamine,tetra(2-hydroxy-ethyl)ethylenediamine and the like.

Further examples of aminocarboxylic acid salts are the salts ofN-methylglycine, N,N-dimethylglycine, N-ethylglycine,N-isopropylglycine, N-butylglycine, N-nonylglycine,N-(2-aminoethyl)glycine, N-(3-aminopropyl)-glycine, N,N-diethylglycine,N,N-dibutylglycine, N-methyliminodiacetic acid, N-ethyliminodiaceticacid, N-isopropyliminodiacetic acid, N-butyliminodiacetic acid,N-ethyl-N-(2-aminoethyl)glycine, N-methyl-N-(3-amino-propyl)glycine,ethylenediaminetetraacetic acid etc. . . .

R¹ or R² may also be a phosphonomethyl group, wherein the starting aminocompound may be N-phosphonomethylethanol-amine and the resultant aminoacid N-phosphonomethyl-glycine. If, of R¹ or R², one R=phosphonomethyland the other R=—CH₂CH₂OH, the resultant amino acid would beN-phosphonomethyliminodiacetic acid, which may be converted in knownmanner into N-phosphonomethylglycine. If, of R¹ or R², oneR=phosphonomethyl and the other R is an alkyl group, the resultant acidwould be N-alkyl-N-phosphono-methylglycine, which may be converted intoN-phosphono-methylglycine in accordance with U.S. Pat. No. 5,068,404.

The process according to the invention may be performed at a temperatureof 50 to 250° C., preferably of 80 to 200° C., and at a pressure of 0.1to 200 bar, preferably at standard pressure to 50 bar.

The pressure is required because the alcohols have an elevated vapourpressure. If the pressure were too low, the alcohol would also bedischarged when the hydrogen was discharged.

DETAILED DESCRIPTION OF THE INVENTION Example 1 Production of theCatalyst According to the Invention

An alloy consisting of 50% Cu/50% Al is activated with an aqueous sodiumhydroxide solution. The corresponding catalyst is washed until thesodium aluminate has been completely removed. Hexachloroplatinum is thenadded to the suspension of the washed catalyst. The pH value is adjustedand stirring of the suspension is continued. The doped catalyst is thenwashed. The platinum content of the catalyst is 1%. The activity of thiscatalyst for dehydrogenating ethylene glycol is 299 ml of hydrogen perhour per gram of catalyst (c.f. Example 3).

Example 2 Production of the Catalyst According to the Invention

An alloy consisting of 50% Cu/50% Al is activated with an aqueous sodiumhydroxide solution. The corresponding catalyst is washed until thesodium aluminate has been completely removed. Iron(III)chloride is thenadded to the suspension of the washed catalyst. The pH value is adjustedand stirring of the suspension is continued. The doped catalyst is thenwashed. The iron content of the catalyst is 3%.

Example 3

Dehydrogenation of ethylene glycol to yield sodium glycolate and sodiumoxalate by means of the activated catalyst according to the Example isperformed at 108° C. and atmospheric pressure. 70 ml of ethylene glycolare first added to a heterogeneous suspension of 8 grams of catalyst and70 ml of an aqueous sodium hydroxide solution. The suspension is stirredat 400 rpm. The rate of reaction is measured by means of the quantity ofhydrogen evolved between 30 and 90 minutes from the beginning of thereaction. The results are stated as ml of hydrogen per hour per gram ofcatalyst. The activity of this catalyst for dehydrogenating ethyleneglycol is 299 ml of hydrogen per hour per gram of catalyst.

Example 4 (Comparative Example)

An alloy consisting of 50% Cu/50% Al is activated with an aqueous sodiumhydroxide solution. The corresponding catalyst is washed until thesodium aluminate has been completely removed. The activity of thiscatalyst for dehydrogenating ethylene glycol is 205 ml of hydrogen perhour per gram of catalyst.

Example 5 (Comparative Example)

A 50% Cu/50′ Al alloy is activated with an aqueous sodium hydroxidesolution. The corresponding catalyst is washed until the sodiumaluminate has been completely removed. Chromium nitrate is added to thesuspension of the washed catalyst, the pH value adjusted, stirring ofthe suspension is continued and the doped catalyst washed once more. Thechromium content in the catalyst is 2000 ppm. The activity of thiscatalyst for dehydrogenating ethylene glycol is 253 ml of hydrogen perhour per gram of catalyst.

Example 6 (Comparative Example)

A Cu/Al/V alloy is activated with an aqueous sodium hydroxide solution.The corresponding catalyst is washed until the sodium aluminate has beencompletely removed. The content of V in the catalyst is 1%; The activityof the catalyst for dehydrogenating ethylene glycol is 253 ml ofhydrogen per hour per gram of catalyst.

Example 7 Production of Iminodiacetic Acid with Platinum on Raney Copperas Catalyst

The Example illustrates the conversion of diethanolamine (DEA) to yieldthe sodium salt of iminodiacetic acid (IDA) with Pt-doped Raney copperas catalyst.

The tests are performed in a 2 L Büchi autoclave. The autoclave isequipped with a sparging agitator, which is operated at a standard speedof 500 min−1 (sic). The autoclave is equipped with a jacket. Thetemperature in the autoclave may be adjusted by means of a temperaturecontrolled oil bath.

The following materials are initially introduced into the autoclave:

-   -   318.8 g of diethanolamine (3 mol)    -   508 g of aqueous NaOH solution (50 wt. %, 6.3 mol NaOH)    -   64 g of catalyst according to the invention: 1% Pt on    -   Raney copper stored under water    -   370 g of H₂O, ultrasonically degassed

The autoclave is pressurised to 10 bar with nitrogen and adjusted to thereaction temperature (TR=160° C.). Once the reaction has begun, theevolved hydrogen is discharged, with the released quantity beingdetermined by means of a dry gas meter. The reaction is terminated aftera period of 5 h and the autoclave cooled. The reaction products areflushed from the autoclave with degassed water, the catalyst filteredout and the dehydrogenation products analysed by ion chromatography.

As Table 1 shows, the catalyst used may be recycled repeatedly withoutappreciable loss of activity. TABLE 1 Conversion of diethanolamine onPt-doped Raney copper Number of batches with catalyst IDA yield [mol %]1 94.3 2 92.5 3 98.6 4 96.8 5 95.0 6 94.7 7 90.9 8 91.8 9 93.4 10 95.811 97.7 12 93.5 13 95.7 14 92.6 15 90.0 16 n.d. 17 n.d. 18 95.2[n.d. = not determined]

Example 6 Production of Iminodiacetic Acid with Iron on Raney Copper asCatalyst

The following materials are initially introduced into a 2 L autoclave:

-   -   318.8 g of diethanolamine (3 mol)    -   508 g of aqueous NaOH solution (50 wt. %, 6.3 mol NaOH)    -   64 g of catalyst according to the invention: 3% Fe on Raney        copper stored under water    -   370 g of H₂O, ultrasonically degassed

The test is performed in a similar manner to Example 5. The yieldslisted in Table 2 are achieved; no deactivation of the catalyst isobservable even after repeated use of the catalyst. TABLE 2 Conversionof diethanolamine on Fe-doped Raney copper Number of batches withcatalyst IDA yield [mol %] 1 95.3 2 99.1 3 99.0 4 n.d. 5 n.d. 6 91.9 7n.d. 8 n.d. 9 n.d. 10 93.7 11 n.d. 12 n.d. 13 n.d. 14 94.0

Example 7 Comparative Example Production of Iminodiacetic Acid onUndoped Raney Copper

Pure Raney copper (Degussa catalyst BFX 3113W) is used under theconditions of Example 5. The Raney copper exhibits distinct deactivationafter only a few batches.

(Table 3) TABLE 3 Conversion of diethanolamine on Raney copper Number ofbatches with catalyst IDA yield [mol %] 1 91.6 2 82.8 3 68.3 4 51.3

Example 8 Production of Glycine with Platinum on Raney Copper asCatalyst

The following materials are initially introduced into the 2 L autoclave:

-   -   307 g of monoethanolamine (5 mol)    -   420 g of aqueous NaOH solution (50 wt.%, 5.25 mol NaOH)    -   64 g of catalyst according to the invention: 1% Pt on Raney        copper stored under water    -   400 g of H₂O; ultrasonically degassed

The test is performed in a similar manner to Example 5. The yieldslisted in Table 4 are achieved. No deactivation of the catalyst isobservable even after repeated use of the catalyst. TABLE 4 Conversionof monoethanolamine on Pt-doped Raney copper Number of batches withcatalyst Glycine yield [mol %] 1 98.5 2 97.5 3 n.d. 4 n.d. 5 98.1

Example 9 Production of β-Alanine with Platinum on Raney Copper asCatalyst

The following materials are initially introduced into the 2 L autoclave:

-   -   380 g of 3-amino-1-propanol (5 mol)    -   422 g of aqueous NaOH solution (50 wt.%, 5.25 mol NaOH)    -   64 g of catalyst according to the invention: 1% Pt on Raney        copper stored under water    -   250 g of H₂O; ultrasonically degassed

The test is performed in a similar manner to Example 5. The yieldslisted in Table 5 are achieved. No deactivation of the catalyst isobservable even after repeated use of the catalyst. TABLE 5 Conversionof 3-amino-1-propanol on Pt-doped Raney copper Number of batches withcatalyst β-Alanine yield [mol %] 1 98.2 2 98.5 3 n.d. 4 n.d. 5 98.3

Example 10 Production of 2-Aminobutyric Acid with Platinum on RaneyCopper as Catalyst

The following materials are initially introduced into the 2 L autoclave:

-   -   460 g of 2-amino-1-butanol (5 mol)    -   392 g of aqueous NaOH solution (50 wt.%, 5.25 mol NaOH)    -   64 g of catalyst according to the invention: 1% Pt on Raney        copper stored under water    -   140 g of H₂O; ultrasonically degassed

The test is performed in a similar manner to Example 5. The yieldslisted in Table 6 are achieved. No deactivation observable even afterrepeated use of TABLE 6 Conversion of 2-amino-1-butanol on Pt-dopedRaney copper Number of batches with 2-Amino-1-butyric acid yieldcatalyst [mol %] 1 99.2 2 98.1 3 n.d. 4 n.d. 5 98.9

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows the advantage of the catalyst according to the inventionillustrated by the example of the dehydrogenation or conversion ofdiethanolamine to yield iminoacetic acid.

The catalyst according to the invention exhibits a distinctly longerservice life than the undoped Raney catalyst.

1.-3. (canceled)
 4. A process for the catalytic dehydrogenation of analcohol, wherein a Raney Copper is used as catalyst, said catalyst beinga Raney Copper catalyst with an average particle size of from 5 μm to 65μm, which is doped with at least one doping metal selected from thegroup consisting of iron and noble metals and wherein the alcohol is aglycol and/or amino alcohol. 5.-29. (canceled)
 30. A process for thecatalytic dehydrogenation of an alcohol comprising: forming a mixture ofan alcohol which is a glycol and/or amino alcohol, an aqueous basicsolution and an activated Raney Copper catalyst which has an averageparticle size of from 5 μm to 67 μm, and is doped with at least onedoping metal selected from the group consisting of iron and noblemetals, and reacting said mixture to form the desired product.
 31. Theprocess according to claim 30, wherein the Raney Copper catalyst is analloy of copper and aluminum.
 32. The process according to claim 30,wherein the alcohol and resulting carboxylate are stable in stronglybasic solution.
 33. The process according to claim 30 wherein the metalis selected from the groups consisting of Re, Pd, Pt, Ag, Au, Rh, Ir,Ru, Fe and mixtures thereof.
 34. A process for the catalyticdehydrogenation of an alcohol comprising reacting a mixture comprisingan alcohol which is a glycol and/or amino alcohol, a Raney-Coppercatalyst with an average particle size from 5 μm to 67 μm which is dopedwith at least one metal selected from the group consisting of ironand/or noble metals and wherein said Raney-Copper catalyst is preparedfrom a copper/aluminum alloy activated with an aqueous sodium hydroxidesolution, followed by washing the alloy, suspending the alloy in water,adding an iron salt or noble metal salt solution to the resultingsuspension, and adjusting the pH of the solution to a value of from 4 to11.
 35. The process according to claim 34, wherein the metal is selectedfrom the group consisting of Re, Pd, Pt, Ag, Au, Rh, Ir, Ru, Fe andmixtures thereof.
 36. The process for the catalytic dehydrogenation ofan alcohol, wherein a doping metal is alloyed together with copper andaluminum, and is activated by means of aqueous sodium hydroxide solutionand the catalyst is washed.
 37. The process for the catalyticdehydrogenation of an alcohol according to claim 4, wherein the catalystis a Raney-Copper catalyst wherein the initial alloy contains more than50% Cu so that the finished catalyst contains more residual Al thannormally found under the same activation conditions.
 38. The process forthe catalytic dehydrogenation of an alcohol according to claim 4,wherein a catalyst is used which is a Raney-Copper catalyst wherein aninitial alloy of copper and said doping metal is heat treated in air attemperatures higher than 500° C. before activation.